Flora of the Pacific Northwest, first published in 1973, became an instant classic for its innovative style of providing species descriptions in the identification keys and for its comprehensive illustrations of nearly all treated taxa (species, subspecies, and varieties). Students rely on it as an essential primer, while veteran botanists and natural resource managers use it as the definitive reference for the region's flora. This completely revised and updated edition captures the advances in vascular plant systematics over the decades since publication of the first edition. These advances, together with significant changes in plant nomenclature, the description of taxa new to science from the region, and the recent documentation of new native and nonnative species in the Pacific Northwest required a thorough revision of this authoritative work. Flora of the Pacific Northwest covers all of Washington, the northern half of Oregon, Idaho north of the Snake River Plain, the mountainous portion of western Montana, and the southern portion of British Columbia. It accounts for the wild-growing native and introduced vascular plants falling within those boundaries and includes: Treatment of 5,545 taxa (more than 1,000 taxa added from the first edition) Illustrations for 4,716 taxa (1,382 more than the first edition) Nomenclature changes for more than 40 percent of the taxa included in the first edition These enhancements make this new edition the most comprehensive reference on Pacific Northwest vascular plants for professional and amateur botanists, ecologists, rare plant biologists, plant taxonomy instructors, land managers, nursery professionals, and gardeners.